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Tech Sheet Do not discard
8205288 / 4619-651-98861 FOR SERVICE TECHNICIAN’S USE ONLY
PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE
MICROWAVE ENERGYa. Do not operate or allow the oven to be operated with
the door open.b. Make the following safety checks on all ovens to be
serviced before activating the magnetron or other microwave source, and make repairs as necessary:1. Interlock Operation2. Proper Door Closing3. Seal and Sealing Surfaces (Arcing, Wear and Other
Damage)4. Damage to or Loosening of Hinges and Latches5. Evidence of Dropping or Abuse
c. Before turning on microwave power for any service test or inspection within the microwave generating compartments, check the magnetron, waveguide or transmission line, and cavity for proper alignment, integrity and connections.
d. Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and transmission systems shall be repaired, replaced, or adjusted by procedures described in service manual before the oven is released to the owner.
e. A microwave leakage check to verify compliance with the Federal Performance Standard should be performed on each oven prior to release to the owner.
f. Do not attempt to operate the oven if the door glass is broken.
WARNING
Electrical Shock Hazard
Disconnect power before servicing.
Replace all parts and panels before operating.
Failure to do so can result in death or electrical shock.
2
WIRING DIAGRAMSSchematic Diagram
Sym
bol N
otes
BK
: Bla
ckB
U: B
lue
R: R
ed
W: W
hite
G: G
reen
Y:
Yello
w
1BR
Wire
Col
or -
Bro
wn
Wire
No.
- 1
Con
ditio
n: D
oor
Ope
n.
DW
G N
O.
MU
-056
Mag
netr
on
Fus
e
5 W
27 BU
26 B
U
Sec
onda
ryIn
terlo
ckS
witc
h
Rel
ay B
oard
Prim
ary
Inte
rlock
Sw
itch
CF
TT
Cav
ity L
amp
Coo
ling
Fan
Mot
or
Turn
tabl
e M
otor
Hoo
d E
xhau
stFa
n M
otor
P21
/P31
/P32
/P33
/P34
/P35
/P51
/P52
/P53
/P54
/P55
/P56
/P57
/P58
/P61
/P62
/P63
/P64
/P65
/P66
/P67
/P68
/P71
/P72
/P73
/P
74/C
N70
1/C
N70
2/C
N70
3: W
ire to
PC
B C
onne
ctor
s
Hoo
d La
mp
(Coo
ktop
Lam
p)H
LCL
CavityThermostat
46 R
47 R
BR
: Bro
wn
OR
: Ora
nge
TR
:Tra
nspa
rent
CN
702
1 B
R20
Am
p
P81
/P82
/P83
/P84
/P85
/P86
: Wire
to W
ire C
onne
ctor
s
45 Y/G
GY
: Gra
y
CN
703
E70
1
Inve
rter
Mon
itor
Inte
rlock
Sw
itch
L N
G W120V
/125
V,60
Hz
72 R
/ 3C
Rib
bon
Cab
le /
3 C
ore
24 G
MW
Rel
ay49
03
TT
TT Rel
ay49
061P
53
CF
Rel
ay49
01
P52
N
CF
55 W
5P81
50 W
6P81
GN
D
R
HF
BK
CF
FCFA
500m
AF
use
L
P74
1
2 B
R
39 BU
35 BR
56 W
36 R
33 BK
12
Mag
netr
on T
herm
isto
r
Y
TR
TR
1P81
Y
1
HL
HL
32 W
31 W2P
81
P58
51 W
52 W
W
1P84
2P84
1
49 B
K4P
81
4121
3P81
17 B
K
P51
P57 P56
P67
P66
Relay Control Board
P65
1
P61
1CN701
Inve
rter
1P
54
1 P55
65 W
CL
1
P63
The
rmos
tat
Bas
e
1
P62
Doo
rN
FS
Inve
rter
500m
A
Fus
e
4170
22 G
Y
53 BK
2P83
1P83
42 GY
34 BU3 BR
L1 N1
P34
P31
Coi
lR
Cy
Cy
Cx
P32
P33
AC
Lin
e F
ilter
Cx
VD
RV
DR
P35
BK
MW Relayfeedback
1 2
TT
P64
UIB
75G
Y/5
CP
2P
3LC
D
18 B
U
23 O
R
28 B
U
67 B
K
1
RW
P68
Hum
idity
Sen
sor
Wav
egui
deT
herm
osta
t
29 BU
54 BK
R
HFW
BK
Mot
or C
apac
itor
Hoo
d E
xhau
stFa
n M
otor
37 R
1P822P82
10uF
3P82
38 R
58 R
VDR
8P81
UIB Thermistor
BK
BK
BK
R R
FC
FAR
elay
4907
64 B
U62 B
K 63 Y
PR
2P
R 1
7P81
9P81
60 G
59 OR22 G
Y
72 R
/3C
PR
1/2
Pow
er R
esis
tor
61 B
R
4 B
R
Rel
ay49
32R
elay
4931
Rel
ay49
30
37 R
77 R
/8C
Touc
h P
anel
B
oard
76 C
olor
/5C
P86
3600
P6
BR
66 R
BK
BK
BK
BK
P73
1
1
P21
73 W
/2C
74 W
/2C
P85
Hoo
dLi
ght
Sw
itch
70 Y
/3C
71 B
K/R
/10
C
3
Parts Layout(not to scale)
(+) Continuity (-) No Continuity
A. Humidity sensor B. Cavity thermostat—opens at 329ºF
(165ºC), closes at -22ºF (-30ºC) C. Waveguide thermostat—opens at
257ºF (125ºC), closes at -95ºF (-35ºC)D. AC line filter E. Relay boardF. Magnetron thermistor G. Magnetron H. Secondary interlock switch I. Ferrite ring
J. Inverter K. Cooling fan motor L. Motor capacitor
M. Monitor interlock switch N. Primary interlock switch O. Relay control board P. Line fuse (20 amp) Q. Fuse holder R. Hood exhaust fan motorS. Hood (cooktop) lamps T. Power resistor-1 (20 ohm/25 W)
U. Power resistor-2 (41 ohm/50 W)V. Base thermostat—closes at 140ºF
(60ºC), opens at 104ºF (40ºC) W. Turntable motor X. Touch panel (back and front views)Y. Cavity lamp Z. Hood/light switch
AA. Door control assembly (back view) (includes touch panel only)
BB. UIB (user interface board)CC. LCD module
Primary, Secondary, and Monitor Interlock Switch Checkout Procedure
Switch Check By Door Open Door Closed
Primary Interlock
1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Primary Interlock Switch.3. Check from the common terminal (brown wires) to the normally
open terminal (brown/white wires).
- +
1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Primary Interlock Switch.3. Check from the common terminal (brown wires) to the normally
closed terminal (orange wire).
+ -
Secondary Interlock
1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Secondary Interlock Switch.3. Check from the common terminal (green/blue wires) to the
normally open terminal (gray/blue wires).
- +
Monitor Interlock
1. Unplug microwave oven or disconnect power.2. Disconnect the wires at the Monitor Interlock Switch.3. Check from the common terminal (blue wire) to the normally
closed terminal (white wire).
+ -
CD
EFGH
I
J
K
LMNOPQRSTUV
SWX
ABAA
BB CC
X
YZ
4
NOTE: These diagrams are not intended to show a complete circuit; they represent the position of switches during “DOOR OPEN” or “DOOR CLOSED” (continuity checks only).
Door Closed Door Open
TROUBLESHOOTINGDo not continue with the diagnostics of appliance if the household fuse is blown, a circuit breaker is tripped or if there is less than 120-volt power supply at the wall outlet.Complete the following steps before checking microwave oven circuitry:1. Unplug microwave oven or disconnect power.2. Check for loose wiring or incorrect wiring within
microwave oven.
3. Disconnect white wire from power transformer and discharge high-voltage capacitor.
4. All testing must be done with an ohmmeter having a sensitivity of 20,000 ohms per volt DC or greater, and powered by at least a 9-volt battery.
5. All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 8 oz (250 mL) of water in a microwave-safe container.
Inverter and Magnetron Circuit
Hood Exhaust Fan on Low Speed
MonitorInterlockSwitch
PrimaryInterlockSwitch
SecondaryInterlockSwitch
(NC) (NO)(NO) (NC) (NO)L N
MonitorInterlockSwitch
PrimaryInterlockSwitch
SecondaryInterlockSwitch
(NC) (NO)(NO) (NC) (NO)L N
Filter2
49031
BU
CavityThermostatPrimary
InterlockSwitch
MW Relay BUBR
P56
P66CN702
P65
CN
701
CN
703Inverter
Magnetron
12
3
32
1
R
R Relay Control Board
Relay Board
BR
10
SecondaryInterlockSwitch
BK BU
RibbonCable
L
BK BRN
WFilter
RibbonCable
Fuse20 Amp
WaveguideThermostat
BU
Fuse 500mA
4170Inverter
1 2
Fuse 500mA
4170
Inverter
HF
Motor Capacitor
L NFuse
20 AmpBR WBK BR BR
P51BU BUG
Relay Board
P52
R
Filter Filter
CavityThermostat
BU
WaveguideThermostat
R R R GY
W W BR
3P82
2P82 5P81
8P81
4P54
4P53
1P54PR2 PR1Power
Resistor-2Power
Resistor-13P811P82
Relay 4930BK BK BK BR BK
5
Hood Exhaust Fan on High Speed
Hood Exhaust Fan on Medium Speed
Hood Exhaust Fan on MAX Speed Manually
Hood Exhaust Fan on MAX Speed Automatically
Fuse 500mA
4170
Inverter
HF
Motor Capacitor
L NFuse
20 AmpBR WBK BR BR
P51BU BUG
Relay Board
P52
R
Filter Filter
CavityThermostat
BU
WaveguideThermostat
R R R GY
W W BR
3P82
2P82 5P81
8P81
4P54
4P53
1P54PR2 PR1Power
Resistor-2Power
Resistor-13P811P82
Relay 4930BK BK BK BR BK
YGY
7P812P54
Relay 4932
BUOR
3P549P81
Fuse 500mA
4170
Inverter
HF
Motor Capacitor
L NFuse
20 AmpBR WBK BR BR P51 BU BUG
Relay Board
P52
R
Filter Filter
CavityThermostat
BU
WaveguideThermostat
R R R GY
W W BR
3P82
2P82 5P81
8P81
4P54
4P53
1P54PR2 PR1Power
Resistor-2Power
Resistor-13P811P82
Relay4930BK BK BK BR BK
YGY
7P812P54
Relay4931
Fuse 500mA
4170
Inverter
HF
Motor Capacitor
L NFuse
20 AmpBR WBK BR BR P51 BU BUG
Relay Board
P52
R
Filter Filter
CavityThermostat
BU
WaveguideThermostat
R R R GY
W W BR
3P82
2P82 5P81
8P81
4P54
4P53
9P811P82
Relay 4930
BK BU OR 3P54Relay4931
Relay4932
BK
Fuse 500mA
4170
Inverter
HF
Motor Capacitor
L NFuse
20 AmpBR WBK BR BR P51 BU BUG
Relay Board
P52
BK
R
BK
Filter
BaseThermostat
Filter
CavityThermostat
BU
WaveguideThermostat
R R R GY
W W BR
BK4P811P82
3P82
2P82 5P81
8P81
4P54
4P53
BU
6
Cooling Fan Motor Circuit
Turntable Motor Circuit
Door Open—Oven Cavity Light is On
Cooktop Light on Variable Light
4P53CF
2P53
2P83
1P83
CF Relay4901
Relay Board
GY
BU
GBR BR P52P51 Cavity
Thermostat
BR BU BUN
WL
BKFilterFilter
Fuse20 Amp
WaveguideThermostat
BUFuse 500mA
4170
Inverter
4P54W
TT
1P53
Relay Board
BR
W
5P81
R
GBR BRP52P51
CavityThermostat
BR BU BUN
WL
BKFilterFilter
6P81
Fuse20 Amp
TT Relay4906
WaveguideThermostat
BUFuse 500mA
4170
Inverter
Filter
LN
Fuse20 Amp BR
WBK BR B RP51 P52
2P55
Fuse500mA
Inverter
4170
4121
Fuse500mA
3P55
P611 2 3
BU BUG
Relay ControlBoard
Relay Board
P63
OR
1P62
12
Filter
PrimaryInterlock
Switch
CavityThermostat
CavityLamp
1P55
BU
WaveguideThermostat
RR
L NFuse
20 AmpBR WBK BR BR
P51 P52BU BUG
Relay Board
Fuse500mA
Inverter
P582
1 W
W
W
TR
Y
W
TR
Y
HL HL
1P84
2P84
2P81
1P81
4170Filter Filter
CavityThermostat
BU
WaveguideThermostat
7
Touch Panel
Touch Panel and Relay Control Board Tests
To access the test mode:1. Unplug microwave oven or disconnect power.2. Open the microwave oven door.3. Press and hold OFF/CANCEL.
4. Plug in microwave oven or reconnect power.5. Release OFF/CANCEL and close microwave oven door.NOTE: If the OFF/CANCEL key is pressed during this diagnostic routine, you will exit the test mode.
Test Mode Table
Microwave Oven Power Output Test1. Place 8 oz (250 mL) of lukewarm water in the center of the
microwave oven.2. Operate on HIGH power level for 2 minutes. Water
should be hot.
NOTE: If the water takes longer than 2 minutes to heat, this may indicate either the operating voltage is lower than 110 volts or there is a problem with the microwave oven.
Screen Display Display Explanation
UIB SW ver Version number of UIB (user interface board) software
PB SW Ver Flash Version number of power board (relay control board) software
UIB thermistor (ºC) The temperature (ºC) measured by UIB thermistor—ranges about 5ºC above room temperature, if oven has not been used recently
Magnetron thermistor (ºC)
The temperature (ºC) measured by magnetron thermistor—maximum 125ºC
HUM PWM Humidity level inside unit—ranges between 8,000 and 9,500, depending on humidity level in oven cavity
Hood Key Hood key number
Screen Display Display Explanation
Touch panel Touch panel error
EEPROM Version number of PB (relay control board) EEPROM (Electrically Erasable Programmable Read-Only Memory)
MW reply error MW relay error
Smps FB error Inverter feedback error
Hum sensor error Humidity sensor error
Cavity thermistor error Cavity thermistor error
Magnetron thermistor error
Magnetron thermistor error
EEPROM error EEPROM (Electrically Erasable Programmable Read-Only Memory) error
8
Failure Codes IndicationsNOTE: Many of the problems listed in the chart below may be solved by power cycling: unplug microwave oven or disconnect power. After one minute, plug in microwave oven or reconnect power.
Display Likely Failure Condition Recommended Repair Procedure
F1.E1 Relay control board defective
1. Unplug microwave oven or disconnect power.2. Replace the relay control board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.
F2.H1 Hood keys stuck 1. Unplug microwave oven or disconnect power.2. Replace hood/light switch. 3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.
F2.H2 Hood/light switch defective
1. Unplug microwave oven or disconnect power.2. Replace hood/light switch.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.
F2.Q1 Not reading keypad inputs
1. Unplug microwave oven or disconnect power.2. Replace the user interface board (UIB).3. Replace the door control assembly.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.
F3.H1 Humidity sensor 1. Unplug microwave oven or disconnect power.2. Check connection to relay control board.3. Replace humidity sensor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.
F3.T1 UIB (user interface board) thermistor
1. Unplug microwave oven or disconnect power.2. Check the connections from the UIB to the relay control board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace relay control board.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.9. If problem persists, unplug microwave oven or disconnect power.10. Replace the UIB.11. Replace all parts and panels before operating.12. Plug in microwave oven or reconnect power.
F3.T3 Hood thermistor 1. Unplug microwave oven or disconnect power.2. Check hood thermistor connection.3. Replace the hood thermistor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace the relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.
9
F3.T4 Magnetron thermistor 1. Unplug microwave oven or disconnect power.2. Check magnetron thermistor connection.3. Replace the magnetron thermistor.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power. 7. Replace the relay control board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.
F6 MW relay 1. Unplug microwave oven or disconnect power.2. Check the cable from Relay 4903 to inverter.3. Check to see if the relay (4903 on relay control board) contact has welded
closed.4. Replace all parts and panels before operating.5. Plug in microwave oven or reconnect power.6. If problem persists, unplug microwave oven or disconnect power.7. Replace relay board.8. Replace all parts and panels before operating.9. Plug in microwave oven or reconnect power.10. If problem persists, unplug microwave oven or disconnect power.11. Replace relay control board.12. Replace all parts and panels before operating.13. Plug in microwave oven or reconnect power.
F7 Power to magnetron interrupted
1. Unplug microwave oven or disconnect power.2. After 40 seconds, check to see whether this solves the problem. 3. Unplug microwave oven or disconnect power.4. Check cooling fan operation5. Check the magnetron.6. Check P65 connection on the relay control board.7. Check the P56/P66 connection between relay board and relay control
board.8. Check wiring to the 1200W inverter and control system. See “Checking
Inverters.”9. Check operation of all interlock switches. 10. Replace all parts and panels before operating.11. Plug in microwave oven or reconnect power.12. Check voltage at 4903-1 on relay board. If it is 120, unplug microwave
oven or disconnect power.13. Replace inverter. 14. Replace all parts and panels before operating.15. Plug in microwave oven or reconnect power.16. If problem persists, unplug microwave oven or disconnect power.17. Replace relay control board.18. Replace all parts and panels before operating.19. Plug in microwave oven or reconnect power.20. If problem persists, unplug microwave oven or disconnect power.21. Check for reversed plug connection on controls or loose wiring.22. Replace all parts and panels before operating.23. Plug in microwave oven or reconnect power.
F9 Relay control board communications error
1. Unplug microwave oven or disconnect power.2. Check the communications cable from P66 to P56 between relay control
board and relay board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace the relay board and relay control board.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.
Display Likely Failure Condition Recommended Repair Procedure
10
Component Tests
F9.Q Touch communication 1. Unplug microwave oven or disconnect power.2. Check the communications cable from UIB to the touch panel board.3. Replace all parts and panels before operating.4. Plug in microwave oven or reconnect power.5. If problem persists, unplug microwave oven or disconnect power.6. Replace the door control assembly.7. Replace all parts and panels before operating.8. Plug in microwave oven or reconnect power.
IMPORTANT:
■ Unplug microwave oven or disconnect power.■ Remove the lead wires from the related component
before conducting any of the following tests.■ Discharge the high-voltage capacitor and remove the
lead wires from the primary winding of the high-voltage transformer before conducting any of the following tests.
■ All operational checks using microwave energy must be done with the microwave oven loaded with a minimum of 8 oz (250 mL) of water in a microwave safe container.
■ Conduct a microwave energy test after performing any tests or repairs to the microwave oven.
■ Check that all wire leads are in the correct position before operating the microwave oven.
■ Grasp wire connectors when removing the wire leads from microwave oven parts.
■ All testing must be done with an ohmmeter having a sensitivity of 20,000 ohms per volt DC or greater, and powered by at least a 9-volt battery.
Components Tests/Results
Magnetron 1. Unplug microwave oven or disconnect power.2. Remove wire leads. Check that the seal is in good condition.3. Measure resistance:
■ Filament terminals: Normal: Less than 1 ohm■ Filament to chassis: Normal: Infinite
Cooling Fan Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 41 +/- 5 ohms■ Abnormal: Infinite
Turntable Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 2.2k +/- 0.5k ohms (approximate)■ Abnormal: Infinite
Hood Exhaust Fan Motor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Pins 1 and 2: Normal: 17 +/- 5 ohms; Abnormal: Infinite■ Pins 1 and 3: Normal: 21 +/- 5 ohms; Abnormal: Infinite
AC Line Filter 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ P31 and P32, P33 and P34: Normal: Greater than or equal to 300k ohms; Abnormal: Less than or equal to 100k ohms
■ P31 and P34, P32 and P33: Normal: 0 ohms; Abnormal: Greater than or equal to 100k ohms
Display Likely Failure Condition Recommended Repair Procedure
1 2 3BK
W
R
P34
P31
P33
P32
11
Humidity Sensor 1. Unplug microwave oven or disconnect power.2. Remove the 3-pin connector from Relay Control Board.3. Measure resistance across pins 1 and 3, and across pins 2 and 3:
■ Normal: 2.8k ohms (approximate) at 77º +/- 10ºF (25º +/- 10ºC)■ Abnormal: Infinite
Thermostats NOTE: Refer to “Parts Layout” for opening and closing temperatures.1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure continuity:
■ Cavity and Waveguide Thermostats: Normal: Continuity; Abnormal: Infinite■ Base Thermostat: Normal: Infinite; Abnormal: Continuity
Magnetron Thermistor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 10k +/- 5% ohms at 77ºF (25ºC)■ Abnormal: Infinite
Motor Capacitor 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: Momentarily 0 ohms, then goes to infinite■ Abnormal: Infinite
Cavity / Hood Lamp 1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 1.5 +/- 0.5 ohms■ Abnormal: Infinite
Relay Control Board NOTE: Do not try to repair or make adjustments to the relay control board.1. Unplug microwave oven or disconnect power.2. Check wiring to relay control board.3. Visually inspect P61, P62, P63, P64, P65, P66, P67, P68, P71, P73 and P74 to see
whether there are signs of overheating or any signs of failure due to loose wires, bad crimping, etc.
Hood / Light Switch NOTE: Do not try to repair or make adjustments to the hood/light switch.1. Unplug microwave oven or disconnect power.2. Check wiring to hood/light switch.3. Visually inspect P21 to see whether there are signs of overheating or any signs of
failure due to loose wires, bad crimping, etc.
Power Resistor-1(20 ohm/ 25 W)
1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 20 +/- 2 ohm at 77ºF (25ºC)■ Abnormal: Infinite
Power Resistor-2 (41 ohm/50 W)
1. Unplug microwave oven or disconnect power.2. Remove wire leads.3. Measure resistance:
■ Normal: 41 +/- 2 ohm at 77ºF (25ºC)■ Abnormal: Infinite
Relay Board NOTE: Do not try to repair or make adjustments to the relay board.1. Unplug microwave oven or disconnect power.2. Check wiring to relay board.3. Visually inspect P51, P52, P53, P54, P55, P56 and P57 to see whether there are
signs of overheating or any signs of failure due to loose wires, bad crimping, etc.
Components Tests/Results
123
Y/G
BKRW
Cavity / WaveguideThermostat
BaseThermostat
31
21
1P
62
1P
61
61
52
P6
31
P6
6
P6
41
P6
8
70
01
46
25
P6
51
P6
71
P7
11
P7
31
P7
41
P21
P224501
45024503
49
14
49
04
49
24
49
05
P52
P51
31
1049
06
49
01
49
07
1P53
3191
49314932
1P54
4903
4121
P54
1
P56
P57
1
4170
P581
5174
5170
Checking Inverters
Measure Oven Input Current
Connect an ammeter (Valhalla Scientific 2101 or equivalent recommended) to measure the input current of microwave oven when the power level is set to Level 10 at the touch panel.
If more than 0.5A:The 1200W inverter is probably OK. Check the magnetron. See Magnetron test in “Component Tests.”
If less than 0.5A:There is no input to the 1200W inverter. Check the following:1. Unplug microwave oven or disconnect power.2. No AC voltage supply. Check relay control board and
wiring.3. No control signal. Check relay control board and wiring.
Check the 1200W Inverter
NOTE: Do not try to repair the inverter board, nor try to make any adjustments to the board.
Check wiring to 1200W inverter:1. Unplug microwave oven or disconnect power.2. Visually inspect 4 connectors on the 1200W inverter
board, CN701, CN702, CN703, E701, to see whether there are signs of overheating or any signs of failure due to loose wires, bad crimping, etc.
15A
Amps
A. CN702B. Heat sinkC. E701D. High-voltage output
to magnetron
E. CN703F. Control signal in/outG. CN701H. 120V AC
B
G
A
C
D
EF
H
8205288 / 4619-651-988613/06
FOR SERVICE TECHNICIAN’S USE ONLY